Screw-propeller



C. B. WALKER.

SCREW PROPELLER.

APPLICATION FILED JULY 7, 1920.

Ill

Patented Apr. 12, 1921.

CHARLES BELL WALKER, OF MOSELEY, ENGLAND.

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' Specification of Letters Patent.

Application filed July 7, 1920. Serial No. 394,531.

7 '0 all wlwm it may concern:

Be it known that I, CnAnLns BELL WALKER, a subject of the Klng of (ireatBritain, and residin at Moseley, 1n the county of Warwick, lungland,have invented certain new and useful Improvements in Screw-Propellers,of which the following is a specification.

This invention relates to screw propellers having blades which can .beturned about their longitudinal axes to alter their pitch or cause themto be reversed through the medium of an electric motor which is rigidlycarried within the boss of the propeller, and has for its object toeffect certain unprovements therein. The improvements, according to thisinvention, comprise the means whereby the motion of the motor istransmitted to the blades and also the means by which the blades aremounted in relation to the boss. These improvements are illustrated inthe drawings herewith, of which- Figure 1 is a sectional plan view ofthe boss of a screw propeller of a navigable vessel, the section beingtaken in the plane indicated by the line 1-1 of Fig. 2, arrangedaccording to a convenient method of carrying out one of the features ofthis invention. I

Fig. 2 is a transverse sectional .yiew of the boss, the section bemgtaken partly on the line 2-2 of Fig. 1 and partly on the line 2%- x ofFig. 1; and,

Fig. 3 is a half plan view of the boat, but with the blade axesvertical. The upper blade is omitted to show the parts beneath.

A single reversible electric motor 3 1s rigidly carried within the nose4 of the boss 5 with the axis of its armature coincident with the axisof the boss, and with its commutator end toward the point of the nose.On the other end of the armature shaft is drivingly mounted a relativelysmall pinion 6 gearing with -a pair of planet wheels 7 of relativelylarge diameter (one for each propeller blade) which are drivinglymounted each upon a shaft 8 which is parallel to the propeller shaft 9and journaled in bearings 10 which are fixed in relation to the boss. Onthe other end of each parallel shaft is a worm 11 meshing with the wormwheel 12 drivingly mounted upon the end of a shaft 13 parallel to theaxis of the respective blade 14 and having at its outer end a pinion 15which gears with teeth 16 cut in the interior face of a crown ring 17mounted rigidly the reversal of the pitch.

upon the inner end of the blade 14 or formmg an integral part thereof.Each blade is mounted in roller or ball bearings 18 of the boss in amanner to permit of the desired amount of rotation in relation to theboss, to allow of the desired alteration of pitch or of It will benoticed that the ball bearing 18 is of very large diameter relatively tothe boss and the purpose of this is to resist to the greatest extent thebending moment of the blades upon the boss due to their thrust.

According to a convenient arrangement two sets of field coils areprovided wound in opposite directions and each connected at one end toone of a pair of slip rings 19, 20, on the propeller shaft. Each fieldcoil 1s connected at its other end to one of the armature terminals, theother armature terminal being earthed. Thus by connecting a source ofcurrent to one of the slip rings, the motor is caused to run in onedirection, and alternatively by connecting such source to the other slipring the motor is caused to run in theopposite direction. By suitablyproportionm'g the gearing, as shown, between the motor and eachpropeller blade, the motor may be caused to rotate a great number oftimes for a very small rotation of the blades on their axes, so that themotor may be very small in relation to the propeller, while havingsuflicient power to operate the blades even when they are under fullload. It will now be readily under stood, that, except when the motor isrunning, there is no movement relative to the boss of the parts withinit, and that they do not in any way interfere with the main drive of thepropeller.

Having fully described what I claim and desire ters Patent is:- i I 1.Means for altering or reversing the pitch of a screw propellercomprising an electric motor rigidly mounted in the nose of the boss ofthe propeller and turning as a whole therewith and having its axisdisposed in substantially the same direction as the axis of thepropeller shaft, a shaft of my invention, to secure by Let- PatentedApr. 12, 1921.

said motor, a pinion of relatively small diameter on said shaft gearingwith a number of pinions of relatively large diameter (one for eachpropeller blade,) shafts upon which such pinions are mounted, saidshafts being parallel to the propeller shaft and turning in bearingswhich are rigid therepitch of a screw propeller comprising an with, andmeans by which the motion of such shafts is transmitted to the blades ofthe propeller to turn them in one or other direction to alter the pitchor to cause them to be reversed. v

2. Means for altering or reversing the which such pinions are mounted,said shaftsbeing parallel to the propeller shaft and turning in bearingswhich are rigid therewith, worms of relatively small diameter on saidparallel shafts, wortm wheels of relatively large diameter -meshing withsaid worms, shafts at right angles to the propeller shaft carrying saidworm wheels and mounted in bearings which are rigid with the propellershaft, and means whereby the motion of such shafts is transmitted to thepropeller blades to turn them in one or other direction to alter thepitch o-rto causethem to be reversed.

3. Means for altering or. reversing the pitch of a screw propellercomprising an electric motor rigidly mounted inthe nose of the boss ofthe propeller and turning as a whole therewith and having its axisdisposed in substantially the same direction as the axis of thepropeller shaft, a shaft of said motor, a pinion of relatively smalldi-.

ameter on said shaft gearing with a number of pinions of relativelylarge diameter (one for each propeller blade) shafts upon which suchpinions are mounted, said shafts being parallel to the propeller shaftand turning in bearings which are rigid therewith,

' worms ofrelatively small diameter on said parallel shafts, worm wheelsof relatively large diameter meshing with said worms, shafts at rightangles to the propeller shaft carrying said Worm wheels and mounted inbearings which are rigid with the propeller shaft, pinions carried oneupon each said shaft which is at right angles to the propeller shaft anda toothed crown ring integral with each propeller blade gearin with therespective pinion Whichis carrie upon the respective shaft which is atright angles to the propeller shaft.

4. In a screw propeller, meansby which the blades thereof may have theirpitch altered or be reversed through the medium of an electric motorwhich is mounted within the boss of the propeller, bearings for theblades arranged to have a considerable width in a direction parallel tothe central axis of the propeller and crown wheels attached to theblades and engaging said bearings within said boss, whereby the bladesare strongly supported from the boss to resist bending moment inrelation thereto due to the thrust of the blades, and transmittingmechanism between said crown wheels and the electric motor.

In witness whereof I have hereunto signed my name this 19th day of June,1920, in the presence of two subscribing Witnesses.

CHARLES BELL WALKER.

